As an apparatus that induces sleep, those that apply stimulation caused by sound to a user, receive a reaction to the applied stimulation from the user who performs a conscious operation, and organize stimulation to be applied to the user by analyzing the reaction have been known (see Patent Literature 1).
According to this Patent Literature 1, for example, synthetic sound whose volume is gradually reduced is given to the user at a constant period as stimulation at the initial stage of sleep. The user presses a button of a joystick as a conscious reaction of listening to the synthetic sound. When the user is in a sleep state, the reaction from the user is lost. The apparatus analyzes this condition, and records the time and elapsed time to sleep, for example. Further, the apparatus analyzes general-purpose data from the user to generate stimulation that produce more favorable effects.